1.Field of the Invention
The present invention generally pertains to digital electronic communications and more particularly to digital electronic communication signals containing an embedded clock signal.
2. Description of the Background
There are two standard communication models for electronic communications, i.e., serial and parallel. Serial communications send all data along a single communications channel. A parallel communication connection is essentially a group of serial communication channels operating together to provide faster data throughput than is possible with a single serial connection. Most serial communication protocols include Fa clock signal embedded within the communication signal. Parallel communication protocols usually send a separate clock channel for clocking the data. For a serial connection, or for each of the serial channels of a parallel connection, a buffer is typically placed at the input of the receiver in order to synchronize the data received with the clock of the receiver. The input buffer is typically implemented as a First-In, First-Out queue, and is called an elasticity FIFO queue.
The elasticity FIFO queue varies in size based on the speed of the communication channel and any possible differences between the clock speed embedded with the communication signal and the clock speed of the receiver device. The greater the difference in clock speeds of the embedded or received clock of the communication signal and the receiver clock, the larger the elasticity FIFO queue necessary.
Most communication protocols include ‘null’ characters as a standard part of data transmission. A null character is a data value that indicates an empty data frame that is not intended to carry any data of the data signal. RapidlO, InfiniBand, Advanced Switching Interconnect (ASI), System Packet Interface (SPI), Fibre Channel, Serial Attached SCSI (SAS), and Serial Advanced Technology Attachment (SATA) are examples of modem communication protocols that employ an embedded clock signal and null characters as part of the communication transmission.
Information on the RapidIO specification is kept by the RapidIO Trade Association, 3925 W. Braker Lane, Suite 325, Austin, Tex. 78759 , telephone number 512-305-0070 , and web site www.rapidio.org. RapidIO is a registered trademark of the RapidIO Trade Association.
Information on the InfiniBand specification is kept by the InfiniBand Trade Association, 5440 SW Westgate Drive, Suite 217, Portland, Oreg. 97221 , telephone number 503-291-2565 , and web site www.infinibandta.org. InfiniBand is a registered trademark of System I/O, Inc., doing business as InfiniBand Trade Association.
Information on the Advanced Switching Interconnect (ASI) specification is kept by the Advanced Switching Interconnect SIG, c/o VTM, 5440 SW Westgate Drive, Suite 217, Portland, Oreg. 97221 , telephone number 503-291-2566 , and web site www.infinibandta.org.
Information on the System Packet Interface (SPI) specification is kept by the Optical Internetworking Forum, 39355 California Street, Suite 307 , Fremont, Calif. 94538 , telephone number 510-608-5928.
Information on the Fibre Channel, SAS, SATA, and many other communication specifications are kept by the American National Standards Institute (ANSI). ANSI is located at 11 West 42nd Street, 13 th Floor, New York, N.Y. 10036 , telephone number 212-642-4900, and web site www.ansi.org.